Understanding medical practices or the whys and wherefores of care decision-making is among the major objectives of medical, economic and sociological research in the current political environment. Although variations of medical practice have long been known to exist, causes and deciding factors remain obscure. This is one of the reasons why medical auditing became widely used in the past years. Using methods similar to those of clinical research, we will explore existing medical practices and their implications, with the aim to propose possible improvements. Elaborating clinical practice guidelines and promoting cancer network activities might prove promising and have a significant impact on clinical practice. This article provides a state-of-the-art overview of the subject, notably in the domain of oncology where substantial advances are being made.